The present invention relates to a superconducting material and more specifically to a superconducting material suited particularly to the electrodes, wirings, etc. of semiconductor devices and the like.
Conventional metallic materials exhibiting superconductivity above the liquid helium temperature (4.2.degree. K.) include metals such as niobium and lead, and alloys such as Nb.sub.3 Sn. Where the electrodes and wirings of a semiconductor device are to be formed from such superconducting materials, it is customary to use niobium, lead or the like capable of being rather easily formed into thin film through electron beam deposition, sputtering or the like process.
Although niobium, lead and the like can be easily formed into thin films, the low melting points thereof present various problems including failure in a high level of heat treatment that is carried out after film formation in the step of producing a semiconductor device; a difficulty in fine patterning through dry etching; and a liability of the characteristics of a thin superconducting film formed therefrom to change in heat cycles between room temperature and a low temperature.
Niobium and lead as the conventional superconducting materials are notably different in characteristics from polysilicon, aluminum, tungsten, etc. used as the materials in customary processes for producing a semiconductor device. This presents a difficulty in producing therefrom a semiconductor device having fine and stable superconducting wirings.
Electrodes and wirings having such an extremely high conductivity as to ward off increase in electric resistance even if they have a decreased cross-sectional area have recently been in strong demand in step with a remarkable progress of miniaturization and an increase in the operation speed of semiconductor devices.
However, the formation of the electrodes and wirings of semiconductor devices from superconducting materials having the highest conductivity has involved the many problems mentioned above and, hence, has encountered a difficulty in materialization thereof.